In the field of semiconductor resists, with developing very large scale integrated circuits, higher minute processing techniques have been demanded. Thereupon, light sources of shorter wavelength such as KrF excimer laser (wavelength: 248 nm), ArF excimer laser (wavelength: 193 nm) and F2 excimer laser (wavelength: 157 nm) are utilized instead of g-ray (wavelength: 436 mm) or i-ray (wavelength: 365 mm) of a conventional high-pressure mercury lamp.
However, even when KrF excimer laser or ArF excimer laser is applied to a conventional resist material such as a novolak resin/diazonaphthoquinone-based positive resist, in which g-ray or i-ray is used, sensitivity and resolution of the conventional resist materials are considerably deteriorated owing to light absorption by the novolak resin.
Moreover, with rises in the integration level and performance of semiconductor integrated circuits, there has been demand for resists with better resolution (patterns in submicron order, quartermicron order or smaller) and for improvement of etching resistance in the process of dry development.
For example, as an approach for improving resolution with the use of conventional process for dry development, there has been known a method in which a photosensitive resin is filled with inorganic fine particles, and silicasol and the like are utilized as the inorganic fine particle to impart both resist performance (sensitivity, resolution, etc.) and dry etching resistance. To illustrate, in order to improve dry etching resistance, Japanese Patent Application Laid-Open No. 158235/1993 (JP-5-158235A) discloses a resist composition comprising a resist composed of a cresol novolak resin and naphthoquinonediazido sulfonic ester, in which silicasol added to the resist, and the resist composition is used as an upper layer resist of bilayer. Japanese Patent Application Laid-Open No. 194491/1999 (JP-11-194491A) proposes a photosensitive resin composition, which comprises a photosensitive organic oligomer or polymer, a hydrolyzable and polymerizable organic metal compound or its condensate, and an inorganic filler having a functional group (e.g., silicasol). Japanese Patent Application Laid-Open No. 327125/1999 (JP-11-327125A) discloses a photosensitive resin composition comprising a photosensitive resin, an inorganic fine particle (e.g., silicasol) or an inorganic fine particle having a functional group. Sondi and Matijevic disclose a film composed of a p-hydroxystyrene-t-butyl acrylate copolymer containing SiO2 nanoparticles (silicasol), and report that the SiO2 nanoparticle is highly soluble in a base to act as a solution accelerator and that the resist including such a SiO2 nanoparticle shows almost the same resolution with control (resist) not comprising SiO2 (I. Sondi and E. Matijevic, Resist Technology and Processing XVII, Francis M. Houlihan, Editor, Proceedings of SPIE Vol. 3999(2000), pp. 627-637). Moreover, this literature discloses that a resist system using a transparent SiO2 nanoparticle is useful to wavelengths such as 157 nm.
On the other hand, with the improvement of miniaturization, recently, edge roughness of resist patterns has been becoming of a problem in particular. The edge roughness is particularly prominent in the resist used in thin films such as surface layer resists.
In the above-mentioned resist comprising a silicasol added thereto, a film can be thickened because the silicasol is small in a particle size and is transparent to exposure beam. Further, owing to the small size of silicasol particle, thin film is also obtainable and resolution thereof can be improved to a certain degree. However, since the resist is dissolved at the area where the resist is inhibited from dissolution (e.g., non-exposed area in the case of positive resist) due to high hydrophilicity of silicasol itself, difference in dissolution rate between exposed area and non-exposed area cannot be increased (enlarged) in the above-mentioned resist, therefore resolution, and sharpness or edge roughness of pattern profile cannot be greatly improved.
Moreover, a commercially available silicasol is mostly manufactured by sodium silicate method, therefore sodium may be inevitably left in the products.
Japanese Patent Application Laid-Open No. 56463/2000 (JP-2000-56463A) discloses that an alcohol solution of a resist material containing an alkali-soluble resin is added with an organooxysilane, and subjected to a sol-gel reaction in the presence of moisture to give a silica-alkali soluble resin hybrid material. In this method, a silica component can be uniformly dispersed in the resist material on molecular level with the silica components prevented from precipitation, by conducting a sol-gel reaction in the resist. However, great improvement of resist performance such as resolution is hardly achieved by this method because the difference in solubility between exposed area and non-exposed area in a developer cannot be enlarged.
Moreover, as a resist composition, there has been known a light-amplifying (chemical-amplifying) resist composition comprising a base resin which becomes alkali-soluble with leaving (removing) by an action of an acid, in combination with a photoactive acid generator. However, the difference in solubility between exposed area and non-exposed area cannot be increased even in this composition.
Accordingly, it is an object of the present invention to provide an active component (including an active particle), that is useful for forming a pattern with high sensitivity and high resolution; a photosensitive resin composition comprising the active component; and a process for forming a pattern using the photosensitive resin composition.
It is another object of the present invention to provide a photosensitive resin composition which improves edge roughness of the pattern with etching resistance against oxygen plasma kept; and a process for forming a pattern.
It is still another object of the present invention to provide a photosensitive resin composition which is efficient for largely improving resolution with high sensitivity to shorter wavelength beams (rays); and a process for forming a pattern using the same.
It is other object of the present invention to provide an active component (including an active particle) useful for forming a pattern with high sensitivity and high resolution in which contamination of impurities is inhibited (avoided); an active metal alkoxide useful for providing the active component; a photosensitive resin composition comprising the active component; and a process for forming a pattern using the photosensitive resin composition.
It is still other object of the present invention to provide a photosensitive resin composition and a process for forming a pattern using the same, which can cause (make) a difference in solubility between exposed area and non-exposed area in a developer.